This work concerns the vasopressin pathway in the hypothalamus originating in the paraventricular nucleus (PVN) and its relationship to the adrenal cortex. The studies are designed to determine which of many extrahypothalamic sites which project to the PVN may carry glucocorticoid inhibitory information, and whether hypercorticism may result from such lesions. Immunoelectron microscopic studies will also be carried out on the PVN system to determine which neurons are the source of the smaller vasopressin granules in nerve terminals on hypophysical portal capillaries.